不同终点检测5种双酚A类化合物对MCF-7的细胞毒性

双酚A(BPA)及其类似物作为聚碳酸酯的主要合成原料,一直是环境污染的重要问题.其雌激素效应是当今科学研究的重点,而毒性效应研究甚少.为评估环境中BPA类物质的毒性效应,实验采用四唑盐(MTS)比色法检测5种双酚A类化合物对人雌激素受体缺失乳腺癌细胞MCF-7(ER-)增殖活性的影响,2,4-二硝基苯肼法检测细胞乳酸脱氢酶(LDH)露出率,单细胞凝胶电泳(SCGE)检测DNA损伤.用非线性最小二乘法对MTS实验结果拟合剂量-效应曲线,表明所有的剂量-效应曲线(DRC)均能用Weibull或者Logit函数有效表征.以模型估算的半数效应浓度负对数值(pEC50)评估5种化合物的毒性大小依次为:BPB>BPC>TDP>BPE>BPA.LDH检测以及SCGE检测受试化合物对MCF-7(ER-)的损伤作用表明,在效应浓度EC20下,细胞核DNA轻微损伤,细胞增殖受轻微抑制;在效应浓度EC40下,细胞核DNA损伤严重,细胞增殖受到显著抑制,从而导致细胞膜通透性显著改变,使LDH大量露出.     

亚硝酸盐型甲烷厌氧氧化微生物特性研究进展

亚硝酸盐型甲烷厌氧氧化(nitrite-dependent anaerobic methane oxidation,N-DAMO)是新近发现的生物反应,是偶联碳氮循环的关键环节,是环境领域和微生物领域的重大发现.N-DAMO的发现对于完善碳氮生物地球化学循环、丰富微生物学内容和研发新型生物脱氮除碳工艺均具有巨大的推动作用.催化N-DAMO反应的微生物为Candidatus Methylomirabilis oxyfera(M.oxyfera),其隶属于一新发现的细菌门——NC10门.近年来,M.oxyfera的生物学研究取得了许多突破性进展,如初步探明了其个体形态特征、细胞化学组分特征、富集培养特征、生理生化特征及生态学特征,最突出的例子包括发现了M.oxyfera独特的细胞(星状)形态及特殊的脂肪酸(10Me C16∶1Δ7)组分等.最近,N-DAMO的机制研究方面也有了突破性进展:发现了地球上第4种生物产氧途径.目前认为,M.oxyfera具有内产氧功能,其首先将NO-2还原为NO,然后将2分子NO进行歧化反应生成N2和O2,最后利用生成的O2对甲烷进行氧化.本文系统地介绍了M.oxyfera各方面的微生物特性.     

Rain‐washing of foliar deposits of Dimilin®WP‐25 formulated in four different carrier liquids

Abstract

Dimilin^® WP‐25, a wettable powder formulation of diflubenzuron (DFB) [1‐(4‐chlorophenyl)‐3‐(2,6‐difluorobenzoyl) urea], was formulated in four different carrier liquids, viz., water; a light petroleum paraffinic oil, ID 585; a heavy paraffinic oil, Sunspray^® 7N; and a 1:2 mixture of a light petroleum aromatic solvent (Cyclosol^® 63) and canola oil; to provide four end‐use mixtures, Dim‐W, Dim‐585, Dim‐7N and Dim‐Cy‐C respectively, each containing 28 g of DFB per litre. Balsam fir branch tips clipped from greenhouse‐grown seedlings, and sugar maple branch tips clipped from field‐grown young trees, were exposed to uniform‐sized droplets (ranging in diameters from 135 to 190 μm) of the four end‐use mixtures which were atomized using a monodispersed droplet generator. Droplets were collected on the fir and maple branch tips and the initial residue per g fresh weight of foliage was determined by high‐performance liquid chromatography (HPLC). The branch tips were exposed to cumulative rainfall of 3, 6 and 10 mm at an intensity of 5 mm/h and at time intervals of 1, 12, 36 and 72 h after DFB treatment, to test the influence of ‘ageing’ of foliar residues on rainfastness. Foliar samples were collected for residue determination just before the onset of rainfall, and at 0.5 h post‐rain. DFB was quantified by the HPLC method. In the case of fir foliage, the Dim‐W formulation was the most susceptible to rain‐washing and the rainfastness did not increase with the ageing period of foliar deposits. In contrast, the three oil‐based mixtures showed greater rainfastness depending upon the carrier liquid and the ageing period. Rainfastness decreased in the order of Dim‐Cy‐C > Dim‐7N > Dim‐585 > Dim‐W. In contrast, the data on maple foliage indicated that the ageing of deposits increased the rainfastness of all the 4 end‐use mixtures. Dim‐585 was the most susceptible to rain washing, and rainfastness decreased in the order of Dim‐W > Dim‐Cy‐C > Dim‐7N > Dim‐585.     

Preliminary indoor radon risk assessment at the Poços de Caldas Plateau,MG-Brazil

This paper aims to present an assessment of the environmental radiological exposure at a Brazilian area of high natural radiation and discusses the indoor radon exposure risk. A survey of inhabitant exposures arising from the inhalation of radon progeny and external gamma exposure was conducted in urban and rural areas of the Po?os de Caldas Plateau, which is recognized worldwide as a high natural radiation region. The results of this survey indicated that highest radiation exposure was restricted to the rural area of Po?os de Caldas. The radiation exposure in urban locations was quite similar to the values observed in normal background areas in some Brazilian counties. By the application of a constant relative risk model, an additional 20% in the lifetime risk of lung cancer mortality due to the exposure to radon progeny was estimated at Po?os de Caldas. It was also estimated that 16% of all lung cancer deaths at Po?os de Caldas county could be attributable to radon exposure.     

T型氧化沟工艺处理低碳源生活污水的效果研究

详细介绍了T型氧化沟工艺的特征,并考察研究了该工艺处理低碳源生活污水的长期运行效果。研究结果表明,工艺出水COD、BOD5、NH3-N、TN和TP年平均浓度分别为13.9、3.8、0.91、18.80和1.67 mg/L,去除率分别为88.99%、94.37%、96.74%、37.57%和41.58%,均能达到相应的排放标准。由于T型氧化沟中以好氧环境为主,缺乏厌氧和缺氧环境以及进水的BOD5/TN值低,工艺对有机物及NH3-N的去除效果较好,但TN和TP去除效果较低。提出了加强工艺脱氮除磷的措施,为同类型污水处理厂改造提供参考。     

Dissipation and effect of chlorophenoxy herbicide on plant pigments and carbohydrates of sunflower (Helianthus annuus L.)

The dissipation pattern of the chlorophenoxy herbicides (2,4‐D and 2,4,5‐T) residues in sunflower plants (Helianthus annuus L.) has been studied along with its effect on the changes of plant pigments (chlorophyll‐a,b, total chlorophyll, carotene and anthocyanin), sugar and starch in different parts of the plant. The residues of 2,4‐D and 2,4,5‐T remained for larger period of time (10 days) at higher concentrations than the lower concentration. The concentrations of chlorophylls and carotene were found to be reduced with the application of both 2,4‐D and 2,4,5‐T. But the chlorophyll concentrations were slowly normalized accompanied with the reduction of the herbicide residues. For anthocyanin, there was no significant effect. In case of carbohydrate, the sugar concentration was found to be raised by all doses in leaf and stem. The change in starch content in different plant parts did not follow an uniform pattern at different doses of herbicides.     

重大自然灾害后遗体处置应急预案研究

重大自然灾害发生后一般都会伴随着大量人员的遇难,及时妥善处置灾后众多遇难者遗体,是许多国家面临的棘手问题。借鉴我国唐山7.8级地震和汶川8.0级地震中遗体应急处置的经验与教训,从遗体的搜集、存放、运输、消毒、防腐、保存、火化、掩埋等方面,探索遗体处理应急预案的程序与内容,从而提高政府应对重大自然灾害后大量遗体的应急处置能力,全面保障灾区群众的身心健康。     

Prenatal diagnosis of de novo (7;19)(q11.2;q13.3) translocation associated with a thick corpus callosum and Wilms tumor of the kidneys

We present a case of prenatal diagnosis of a de novo (7;19)(q11.2;q13.3) translocation associated with ultrasound features, including enlarged cisterna magna, normal vermis, thick corpus callosum, micrognathia, small and low-set ears and right hyperechogenic kidney. Karyotyping was performed at 24 weeks of gestation. Termination of pregnancy was accepted at the parents' request. Postmortem examination confirmed the prenatal findings, but revealed bilateral Wilms tumors of the kidneys. Parental karyotype was normal. Copyright © 2005 John Wiley & Sons, Ltd.     

气体二氧化氯对葡萄表面细菌杀菌规律研究

研究气体二氧化氯杀灭金黄色葡萄球菌、大肠杆菌、李斯特单增菌和腐生酵母菌4种葡萄表面的危险致病菌的杀菌规律。在实验范围内,随着气体二氧化氯浓度的增加和杀菌时间的延长,杀菌效果明显增加。当杀菌时间超过12min,杀菌量级几乎不再增加。杀菌效率随温度的增加而减小,在实验温度条件下,只有大肠杆菌的杀菌效果减少了5.38～6.09log量级,其他3种菌均减少了6log量级以上,杀菌作用温度在实验条件下对杀菌效果影响不大。研究表明,当气体二氧化氯的杀菌浓度为25mgl-1、杀菌时间12min、杀菌温度25℃的条件下,金黄色葡萄球菌、李斯特单增菌和腐生酵母菌均减少了6.4log量级以上,而大肠杆菌达到5.76log量级;同时表明二氧化氯气体的杀菌保鲜功能也是食品安全技术非热杀菌手段。     

颤蚓生物扰动对沉积物氮释放的影响

通过实验室模拟沉积物中颤蚓生物扰动过程,研究了生物扰动对沉积物TN释放的影响,并探讨了温度、pH和DO对颤蚓生物扰动作用下TN释放过程的影响.结果表明,颤蚓生物扰动能促进沉积物TN释放,且促进效果随颤蚓密度的增加而提高.适当地提高温度有助于颤蚓快速生长,提高生物扰动对TN释放的促进效果,温度由15℃提高到25℃,上覆水...